Trilobites are remarkable, hard-shelled, segmented creatures that existed over 520 million years ago in the Earth's ancient seas. They went extinct before dinosaurs even came into existence, and are one of the key signature creatures of the Paleozoic Era, the first era to exhibit a proliferation of the complex life-forms that established the foundation of life as it is today. Although dinosaurs are the most well-known fossil animals, trilobites are also a favorite among those familiar with Paleontology (the study of the development of life on Earth), and are found in the rocks of all continents

THE TRILOBITE BODY PLAN

Whatever their size, all trilobite fossils have a similar body plan, being made up of three main body parts: a cephalon (head), a segmented thorax, and a pygidium (tail piece) as shown above. However, the name "trilobite," which means "three lobed," is not in reference to those three body parts mentioned above, but to the fact that all trilobites bear a long central axial lobe, flanked on each side by right and left pleural lobes (pleura = side, rib). These three lobes that run from the cephalon to the pygidium are what give trilobites their name, and are common to all trilobites despite their great diversity of size and form.

Species

Ptychopariida

Balnibarbi

All Photos on this page are Fossils in my private collection.

The Megalodon was not only the biggest and bad prehistoric shark that ever lived; it was the largest marine predator in the history of the planet. Today’s great white sharks would be a mere bite size snack for this monster. It terrorized the diverse ocean waters around the world from 15.9 to 2.6 million years ago (late Oligocene to early Pleistocene). This massive, extinct species of shark estimated to grow to nearly 60 feet in length and often been declared the greatest vertebrate predator which ever lived.

These mega-tooth sharks were a giant and more robust version of the great white. They had 276 teeth in five rows and like today’s sharks shed their teeth throughout their lifetime. The largest Megalodon teeth on record reached a stagger 7.25 in (184mm). Compare this to the largest great whites whose teeth top out around 3 inches long. Wow.

Their teeth were bone crunching and flesh cutting tools, which evolved for grasping powerful prey such as Baleen whales. Fossil evidence supports that Megalodon focused its attack on the hard boney parts of its prey, such as rib cages, flippers, shoulders, and spines- effectively disabling large whales and harming major organs such as the heart and lungs. This strategy explains the thick, robust teeth of the Megalodon.

Megalodon has a cosmopolitan (global) distribution and its giant teeth are found in deposits throughout the world. Some are collecting on land in phosphate deposits while many are collected from rivers and coastlines after eroding out of the rocks. This contributes to the water worn, polished appearance to many teeth.

The standard measure for Megalodon teeth is slant height, or the longest edge of the tooth. Adult Megalodon teeth were typically in the 4-5 inch range, with teeth over 6 inches being rare and representing super-sized individuals. There have only been a handful of teeth ever found over seven inches.

No one knows for sure why the Megalodon went extinct 2.6 Million years ago, but the cooling of the climate and gradual disappearance of many of the large whales it relied on for food are suspects.